The invention is based on a flat pipe pressure damper for damping fluid pressure pulsations in fluid lines and a fuel supply line for a vehicle.
This kind of flat pipe pressure damper and fuel supply line have been disclosed by EP 0 235 394 A1. The known flat pipe pressure damper is integrated into the fuel supply line of an internal combustion engine. The fuel supply line is divided in its longitudinal direction into an upper, air-filled chamber and a lower, fuel-carrying chamber by an elastic membrane. The flat pipe pressure damper in this case is constituted by the upper, air-filled chamber and the elastic, fuel-tight membrane. The membrane absorbs pressure surges caused by switching pulsations of injection valves and feed pulsations of an injection pump in the lower, fuel-carrying chamber by the fact that this membrane elastically deforms and thereby transmits the pressure pulsations into the air cushion in the upper, air-filled chamber. Through the elastic deformation of the membrane and the resulting compression of the air cushion in the upper, air-filled chamber, oscillation energy is lost, by means of which the pressure pulsations in the lower, fuel-carrying chamber are damped.
The membrane is clamped between an upper part and a lower part of the line wall of the fuel supply line, wherein the edge of the upper part of the line wall is overlapped by the edge of the lower part of the line wall. In addition, an O-ring is inserted between the upper and lower parts of the line wall to create a seal.
The known flat pipe pressure damper has the disadvantage that the upper, air-filled chamber can collapse when there are intense pressure surges of the kind that occur during leak tests, for example. Since the oscillatory membrane is frictionally secured between the upper and lower line wall, the membrane can slip out of its seat when under high stress. A repair is costly since the fuel line involved must be disassembled and a new membrane must be inserted.
Furthermore, the wall thickness of the oscillatory membrane must be adapted to the respective pressure range in which the flat pipe pressure damper is to be used so that a large number of different flat pipe pressure dampers must be produced, which results in correspondingly high manufacturing costs.
The flat pipe pressure damper for damping fluid pressure pulsations according to the invention has an advantage over the prior art that the percentage of non-compressible fluid in the chamber prevents chamber from collapsing when there are intense pressure surges. Since the oscillatory and damping properties of the flat pipe pressure damper according to the invention can be preset as a function of the fluid quantity disposed in the chamber, it is no longer necessary to produce dampers with to different chamber wall thicknesses. As a result, the same flat pipe pressure damper can be used universally for different pressure ranges. Moreover, a selection can be made from among the wall thicknesses being considered for the flat pipe pressure damper, which is the most favorable for manufacturing.
Other advantages arise from the high safety reserves of the flat pipe pressure damper according to the invention so that flat pipe pressure damper is also not damaged by leak tests in which the testing pressures are up to twice the normal operating pressure.
Advantageous improvements and updates of the flat pipe pressure damper disclosed are possible by means of the measures taken hereinafter.
A particularly preferable improvement of the invention provides that one part of the chamber is preferably filled with oil and the other part of the chamber is filled with a gaseous medium, preferably with air at atmospheric pressure. On the one hand, the chamber can produce a favorable damping effect due to the high volumetric elasticity of air. On the other hand, oil has a very low compressibility, as a result of which there is a high degree of protection against a collapsing of the chamber when the elasticity reserves are exceeded.
The apparatus of the flat pipe pressure damper has the advantage that if the pressure damper develops an undesirable leak, no fluid escapes from the fluid line.